Watermelon Mai Tai

• 
  6 cups (35 oz) peeled and chopped seedless watermelon
• 
  2 cups (17 oz) medium oranges

  peeled, pith and seeds removed, halved

• 
  1 cup (8 fl oz) fresh chilled pineapple juice
• 
  ⅓ cup (2¾ fl oz) white rum
• 
  ⅓ cup (2¾ fl oz) triple sec
• 
  1 tsp grenadine

To serve

• 
  Ice cubes
• 
  Watermelon

  cut into wedges